Quasi-solid Dye Sensitized Solar Cells Having Straight Ion Paths Proposal of High-Efficiency QDSCs Consisting of Two Carrier Density Layers

Quasi-solid dye-sensitized solar cells (QDSCs) consisting of amylose/porous Al 2 O 3 film/ionic liquid films (Am-Al/IL film) are reported. The surface of straight nanopores in the Al 2 O 3 film was modified with amylose and these nanopores were filled with ionic-liquid-type electrolytes. The ionic liquid did not leak from these nanopores of the film. The photovoltaic performance of the QDSC consisting of Am-Al/IL films was almost the same as that before the solidification, despite that the film was occupied with 50% of electrochemically inactive Al 2 O 3 wall. It was found that the iodine was adsorbed on the straight wall of Am-Al films and the apparent diffusion coefficient of I - 3 species was almost the same as that in the parent liquid electrolyte. From these results and our previous reports, we propose QDSC structures consisting of two-carrier-density layers (I - /I - 3 ) with low and high carrier concentrations for high-efficiency cells. A bulk area between a counter electrode and a TiO 2 electrode is occupied with a high-carrier-density medium (I - /I - 3 ), and TiO 2 nanopores are filled with a low-carrier-density medium (I - /I - 3 ). The former increases the conductivity and the latter suppresses the back electron transfer from the TiO 2 layer to redox species.